Monolayer graphite (i.e., graphene) has attracted interest over the past decade, which has in turn spurred interest in few-layer and monolayer hexagonal boron nitride (h-BN). Independent of the number of layers, h-BN is a wide band gap (˜5.5 eV) insulator with higher oxidation resistance than, and comparable mechanical strength to, graphene. These and other characteristics make h-BN a potential candidate in various applications such as filler for mechanically enhanced polymer composites, oxidation resistant coatings for aerospace technologies, neutron shielding barriers, and scaffolds for high temperature combustion gas sensors. As a substrate for other 2D materials, h-BN has been shown to reduce charge density fluctuation and surface roughness, leading to enhance electronic properties in overlaid graphene and enhanced optoelectronic properties in overlaid transitional metal dichalcogenides.
Despite these novel characteristics and promising applications, the intrinsic properties of few-layer h-BN, in particular structural properties, have not been studied as extensively as those for graphene. Limited electron microscopy investigations of h-BN have revealed the atomic structure of point defects, step edges, and grain boundaries at room temperature, and grain boundaries at 450° C., but analogous high temperature (above 500° C.) defect formation, stability, and dynamics studies are very limited. The elevated temperature atomic-scale characteristics of h-BN are important in understanding the physical, mechanical and chemical properties of h-BN for future harsh-environment applications.